Question

我是编程新手，如果您可以帮助我，那将是很棒的。我有一个带有按钮和列表视图的活动。列表视图上的值是名称，价格，类别和数量，并通过适配器定义。我想知道如何将每行的数量值与价格值相乘并求和所有这些值，并在单击按钮时在烤面包中显示结果。 Here's对其进行图形处理以更好地理解它。

代码如下：

CartListActivity.java

public class CartListActivity extends AppCompatActivity {

    ListView userList;
    UserCustomAdapter userAdapter;
    ArrayList<User> userArray = new ArrayList<User>();

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_cart_list);

        Button payBtn = (Button)findViewById(R.id.payBtn);
        payBtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Toast.makeText(getApplicationContext(), "Total: x€", Toast.LENGTH_SHORT).show();
            }
         });

        /**
         * add item in arraylist
         */
        userArray.add(new User("Olives verdes", "1,20€", "Aperitius", "0"));
        userArray.add(new User("Olives negres", "1,30€", "Aperitius", "0"));
        userArray.add(new User("Cogombrets", "1,80€", "Aperitius","0"));
        userArray.add(new User("Patates Lay's", "1,19€", "Aperitius","0"));
        userArray.add(new User("Potet", "0,95€", "Bebè","0"));
        userArray.add(new User("Biberó", "3,85€", "Bebè","0"));
        userArray.add(new User("Tovalloletes", "1,10€", "Bebè","0"));
        userArray.add(new User("Perxes de nadó", "1,95€", "Bebè","0"));
        /**
         * set item into adapter
         */
        userAdapter = new UserCustomAdapter(CartListActivity.this, R.layout.view_row,
                userArray);
        userList = (ListView) findViewById(R.id.listView);
        userList.setItemsCanFocus(false);
        userList.setAdapter(userAdapter);
        /**
         * get on item click listener
         */
        userList.setOnItemClickListener(new OnItemClickListener() {

            @Override
            public void onItemClick(AdapterView<?> parent, View v,
                                    final int position, long id) {
                Log.i("List View Clicked", "**********");
                Toast.makeText(CartListActivity.this,
                        "List View Clicked:" + position, Toast.LENGTH_LONG)
                        .show();
            }
        });

    }

}

UserCustomAdapter.java

public class UserCustomAdapter extends ArrayAdapter<User> {
    Context context;
    int layoutResourceId;
    ArrayList<User> data = new ArrayList<User>();

    public UserCustomAdapter(Context context, int layoutResourceId,
                             ArrayList<User> data) {
        super(context, layoutResourceId, data);
        this.layoutResourceId = layoutResourceId;
        this.context = context;
        this.data = data;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        View row = convertView;
        UserHolder holder = null;

        if (row == null) {
            LayoutInflater inflater = ((Activity) context).getLayoutInflater();
            row = inflater.inflate(layoutResourceId, parent, false);
            holder = new UserHolder();
            holder.textName = (TextView) row.findViewById(R.id.textView1);
            holder.textPrice = (TextView) row.findViewById(R.id.textView2);
            holder.textCategory = (TextView) row.findViewById(R.id.textView3);
            holder.textQuantity = (TextView) row.findViewById(R.id.quantityTxt);
            holder.btnEdit = (Button) row.findViewById(R.id.button1);
            holder.btnDelete = (Button) row.findViewById(R.id.button2);
            row.setTag(holder);
        } else {
            holder = (UserHolder) row.getTag();
        }
        final User user = data.get(position);
        holder.textName.setText(user.getName());
        holder.textPrice.setText(user.getPrice());
        holder.textCategory.setText(user.getCategory());
        holder.textQuantity.setText(user.getQuantity());
        final UserHolder finalHolder = holder;
        holder.btnEdit.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {

                String value1 = finalHolder.textQuantity.getText().toString();
                int a = Integer.parseInt(value1);

                if(a <= 99) {
                    int sum = a + 1;

                    Log.i("Edit Button Clicked", "**********");
                    user.setQuantity(Integer.toString(sum));
                    finalHolder.textQuantity.setText(Integer.toString(sum));
                }
            }
        });
        holder.btnDelete.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {

                    String value2 = finalHolder.textQuantity.getText().toString();
                    int a = Integer.parseInt(value2);

                    if(a > 0) {
                        int substract = a - 1;
                        Log.i("Delete Button Clicked", "**********");
                        user.setQuantity(Integer.toString(substract));
                        finalHolder.textQuantity.setText(Integer.toString(substract));
                    }
            }
        });
        return row;

    }

    static class UserHolder {
        TextView textName;
        TextView textPrice;
        TextView textCategory;
        TextView textQuantity;
        Button btnEdit;
        Button btnDelete;
    }
}

User.java

public class User {
    String name;
    String price;
    String category;
    String quantity;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getPrice() {
        return price;
    }

    public void setPrice(String price) {
        this.price = price;
    }

    public String getCategory() {
        return category;
    }

    public void setCategory(String category) {
        this.category = category;
    }

    public String getQuantity() {
        return quantity;
    }

    public void setQuantity(String quantity) {
        this.quantity = quantity;
    }

    public User(String name, String price, String category, String quantity) {
        super();
        this.name = name;
        this.price = price;
        this.category = category;
        this.quantity = quantity;
    }

}

Answer 1

希望我没有解决您的问题，如果您遍历payBtn onClick方法内的userArray列表并获得总和，该怎么办？像这样的东西：

Button payBtn = (Button)findViewById(R.id.payBtn);
    payBtn.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            int total = 0;
            for(User u: userArray){
                total += (u.getPrice()*u.getQuantity());
            }

            Toast.makeText(getApplicationContext(), "Total: +total+"€", Toast.LENGTH_SHORT).show();
        }
     });

Answer 2

因此，对于您的设计，正如我在您的代码中看到的那样，您有一个arrayList，其中包含所有创建的项目。我会做这样的事情（在您的活动类中创建此函数）：

public class CartListActivity extends AppCompatActivity {

ListView userList;
UserCustomAdapter userAdapter;
ArrayList<User> userArray = new ArrayList<User>();

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_cart_list);

    Button payBtn = (Button)findViewById(R.id.payBtn);
    payBtn.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            Toast.makeText(getApplicationContext(), "Total: x€", Toast.LENGTH_SHORT).show();
        }
     });

    /**
     * add item in arraylist
     */
    userArray.add(new User("Olives verdes", "1,20€", "Aperitius", "0"));
    userArray.add(new User("Olives negres", "1,30€", "Aperitius", "0"));
    userArray.add(new User("Cogombrets", "1,80€", "Aperitius","0"));
    userArray.add(new User("Patates Lay's", "1,19€", "Aperitius","0"));
    userArray.add(new User("Potet", "0,95€", "Bebè","0"));
    userArray.add(new User("Biberó", "3,85€", "Bebè","0"));
    userArray.add(new User("Tovalloletes", "1,10€", "Bebè","0"));
    userArray.add(new User("Perxes de nadó", "1,95€", "Bebè","0"));
    /**
     * set item into adapter
     */
    userAdapter = new UserCustomAdapter(CartListActivity.this, R.layout.view_row,
            userArray);
    userList = (ListView) findViewById(R.id.listView);
    userList.setItemsCanFocus(false);
    userList.setAdapter(userAdapter);
    /**
     * get on item click listener
     */
    userList.setOnItemClickListener(new OnItemClickListener() {

        @Override
        public void onItemClick(AdapterView<?> parent, View v,
                                final int position, long id) {
            Log.i("List View Clicked", "**********");
            Toast.makeText(CartListActivity.this,
                    "List View Clicked:" + position, Toast.LENGTH_LONG)
                    .show();
        }
    });

}
private double getTotalPrice(){
    double total = 0;
    if (userArray.size() == 0){ return total;}
    else {
        for (User user : userArray ) {
            double price = Double.parseDouble(user.getPrice()); // assuming you price is a string , and that you have getters and setters for all of the user's fields
            int quantity = Integer.parseInt(user.getQuantity());
            total = price*quantity;
        }
        return total;
    }

}

（如果语法方面有问题，我将编辑答案）然后在您的onClick中：

        payBtn.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            double totalPrice = getTotalPrice();
            String msg = String.format("Total: %f€" , totalPrice ) // %f because the function returns double
            Toast.makeText(getApplicationContext(), msg , Toast.LENGTH_SHORT).show();
        }
     });

Answer 3

    yourButton.setOnClickListener(new View.OnClickListener() {
        long total=0;
        for(User u:userArray){
          String priceAsString=u.getPrice();
          String priceWithOutCamma=priceAsString.replaceAll(",","");
          String priceWithOutSign=priceWithOutCamma.replaceAll("€","");
          int price=Integer.valueOf("priceWithOutSign");
          int quantity=Integer.valueOf(u.getQuantity());
          total+=price*quantity;
       }
    DecimalFormat format=new DecimalFormat("#,###");
    String totalFormatted=format.format(total);
    Toast.makeText(getApplicationContext(), "Total: " +totalFormatted+"€", Toast.LENGTH_SHORT).show();
}

如何对ListView中的TextViews的值求和并相乘，并在烤面包中显示它们？

3 个答案: